A 51-year-old woman was referred to our hospitalfor treatment of endometrialcancer. She had 3 family members with colorectal cancer in the first degree. She was also diagnosed with advanced cecal cancer based on a preoperative examination. She underwent laparoscopic surgery, modified radical hysterectomy, and bilateral salpingo-oophorectomy for endometrial cancer, and ileocecal resection for cecal cancer simultaneously. Pathological examination of the uterine tumor revealed carcinosarcoma with carcinomatous and sarcomatous components. Since she fulfilled 4 of the revised Bethesda criteria, we suspected Lynch syndrome. Immunohistochemical analysis of mismatch repair proteins demonstrated the loss of MSH2/MSH6 expression in both cecalcancer and uterine carcinosarcoma tissues. Genetic testing by direct sequencing revealed a pathogenic germ line mutation of MSH2 in codon 2245 of exon 14, and she was definitively diagnosed with Lynch syndrome. Laparoscopic surgery is less invasive and would be useful for Lynch syndrome patients potentially requiring multiple surgeries or risk- reduction surgery.